hey guys. i have an genuine copy of windows xp cd. my mates HP laptop needs to be reformatted but he hasnt a windows xp cd but his got a genuine cd key number. well i be able to reformat and install xp using his numba or will it say an invalid key because it different to mine. thanks 4 ur help

Yes, you will be able to use your CD with his genuine key. During the setup when it asks you for the key, just put his in.

**IMPORTANT - If the disk you have isn't actually the Windows CD and is made by Dell, Gateway, HP, etc, then it probably won't ask you for a CD key and then you shouldn't use your CD for his computer because you will then both have this same key, which can cause problems.